Configuring IGMP Snooping Global Options

A number of IGMP snooping options can be configured on Ruckus devices in global configuration mode.

You must configure the IGMP mode and version globally before entering these options. See the Configuring the IGMP Snooping Mode and Version Globallytask.

The following option configurations are outlined in the steps below:

  • Modify the age interval for group membership entries—When the device receives a group membership report, it makes an entry for that group in the IGMP group table. The age interval specifies how long the entry can remain in the table before the device receives another group membership report.
  • Modify the query interval (only for IGMP active mode)—If IP multicast traffic reduction is set to active mode, you can modify the query interval to specify how often the device sends general queries.
  • Modify the maximum response time—The maximum response time is the number of seconds that a client can wait before responding to a query sent by the device.
  • Configure report control (v2 only)—A device in passive mode forwards reports and leave messages from clients to the upstream router ports that are receiving queries. You can configure a report control option to rate-limit report forwarding within the same group to no more than once every 10 seconds. This rate-limiting does not apply to the first report answering a group-specific query.
  • Modify the wait time before stopping traffic when receiving a leave message—You can define the wait time before stopping traffic to a port when a leave message is received. The device sends group-specific queries once per second to ask if any client in the same port still needs this group. Due to internal timer granularity, the actual wait time is between n and (n+1) seconds (n is the configured value).
  • Modify the multicast cache age time—You can set the time for an mcache to age out when it does not receive traffic. The traffic is hardware switched. One minute before aging out an mcache, the device mirrors a packet of this mcache to CPU to reset the age. If no data traffic arrives within one minute, this mcache is deleted. A lower value quickly removes resources consumed by idle streams, but it mirrors packets to CPU often. A higher value is recommended when data streams are continually arriving.
  • Enable or disable error or warning messages—The device prints error or warning messages when it runs out of software resources or when it receives packets with the wrong checksum or groups. These messages are rate-limited. You can turn off these messages.

The following task steps can be configured in any order and are all optional. Commands that are limited to a specific IGMP mode or version are identified in the task step.

  1. Enter global configuration mode.
    device# configure terminal
  2. Modify the age interval, in seconds, for group membership entries.
    device(config)# ip multicast age-interval 280
    When multiple devices are connected together, all devices must have the same age interval configured, which must be at least twice the length of the query interval, so that missing one report won't stop traffic. Non-querier age intervals must be the same as the age interval of the querier.
  3. Modify the query interval, in seconds (only for IGMP active mode).
    device(config)# ip multicast query-interval 120
    When multiple queriers connect together, they must all be configured with the same query interval.
  4. Modify the IPv4 multicast maximum response time, in seconds.
    device(config)# ip multicast max-response-time 5
  5. Configure report control (v2 only).
    device(config)# ip multicast report-control
    IGMP V2 membership reports of the same group from different clients are considered to be the same and are rate-limited.
    Note: This feature applies to IGMP V2 only. The leave messages are not rate limited.
  6. Modify the wait time before stopping traffic when receiving a leave message.
    device(config)# ip multicast leave-wait-time 5
  7. Modify the multicast cache age time.
    device(config)# ip multicast mcache-age 180
    Note: The mcache age value configured may not expire accurately. You may notice a delay of 0 to 60 seconds.
  8. Enable or disable error or warning messages.
    device(config)# ip multicast verbose-off

The following example globally sets the device to run IP multicast version 3 in active mode.

device# configure terminal
device(config)# ip multicast age-interval 280
device(config)# ip multicast query-interval 120
device(config)# ip multicast max-response-time 5
device(config)# ip multicast report-control
device(config)# ip multicast leave-wait-time 5
device(config)# ip multicast mcache-age 180
device(config)# ip multicast verbose-off